1. Field of the Invention
The subject invention generally pertains to sectional doors and more specifically to a release mechanism for such a door.
2. Description of Related Art
A sectional door typically includes a series of panels whose adjacent horizontal edges are each pivotally connected by a row of hinges. As the door opens or closes, the door panels travel along two lateral tracks that in one configuration curve between horizontal and vertical. To close the door, the tracks guide the panels to a vertical position. When the door opens, the hinges allow the panels to curve around onto horizontal sections of the tracks, where the door panels store horizontally overhead. In other configurations, the sectional door maintains a generally vertical, planar configuration and is stored more directly above the doorway. Such doors, regardless of their configuration, can be powered up or down or can be manually operated. To ease the operation of the door, a torsion spring is often used to offset the weight of the door panels. Sectional doors are commonly used as residential garage doors; however, they are also often used in warehouses and other industrial buildings.
When used in high-traffic industrial applications, sectional doors are very susceptible to being struck by large trucks, trailers, forklifts and other vehicles passing through the doorway. There are different reasons why vehicles collide with doors. One of the more common causes is a door""s torsion spring becoming weak with age or not being properly preloaded. This can allow a door to droop down into the doorway from a fully open position or not open fully at all. In such cases, an upper edge of a vehicle traveling through the doorway may strike the lower portion of the drooping door, which can damage one or more door panels, as well as damage door-mounting hardware, such as hinges, rollers and track.
Doors are also often installed adjacent to a dock leveler of a loading dock. When the door is closed, such doors can be damaged as material handling equipment stage loads on the dock leveler. For instance, a forklift may accidentally push a load up against the door.
Consequently, some doors are provided with some type of breakaway feature that allows a door to give way to a collision without being damaged. For example, a sectional door described in U.S. Pat. No. 5,727,614 includes a track-following roller that can break away from its mounting bracket in reaction to a collision. After the collision, the roller can be reattached to the bracket. The breakaway device, however, has its limitations. Upon breaking away, the roller can completely separate from the mounting bracket, thus an impact could throw the roller where it may be difficult to find. This is particularly true for a loading dock door that is installed adjacent to a dock leveler. In such cases, the roller may fall into a pit that is underneath a conventional dock leveler or fall into some snow that may be just outside the building. It also appears that the ""614 device breaks away at a predetermined force, which cannot be readily adjusted or altered once the door is installed. Depending on the application, it may be desirable to have a door that breaks away in one direction easier than another. For instance, for heavier doors, it may be desirable to have a higher breakaway force in one direction (from outside to inside), so that the door does not break away under its own weight when fully open and stored overhead. It some cases, for example, it may be beneficial to have a door whose breakaway feature only acts in one direction. In windy areas, it may be better to have a door that only breaks away in an outward direction to avoid the door giving way to strong winds.
Another breakaway device, shown in U.S. Pat. No. 6,039,106 does include a means for adjusting the breakaway force. The breakaway force is adjusted by turning a setscrew, which adjusts the pressure that a spring-loaded plunger exerts against a detent of a track-following guide member. Under sufficient breakaway force, the guide member is able to swing its detent out from underneath the force of the plunger; however, the guide member does not completely separate from the plunger. The swinging motion also releases the guide member out from within the track, which releases the door to avoid damage. Although the device has an adjustable breakaway, it appears that the breakaway force is the same in both directions and that the device cannot be readily locked to disable the breakaway feature.
Other examples of breakaway mechanisms are shown in U.S. Pat. Nos. 5,392,836 and 6,053,237. These devices; however, share some of the same limitations of the other breakaway devices that have already been discussed.
In order to provide a versatile breakaway device for a sectional door, a release mechanism includes a first member for releasably coupling a track-following guide member to a bracket connected to the door. The first member may be able to snap into and out of the guide member to allow the guide member to move between an operative position where the guide member engages the track and a dislodged position where the guide member separates from the track, or the first member may engage or disengage the guide member in other ways.
In some embodiments, the guide member includes a roller.
In some embodiments, the release mechanism releases easier in one direction than another.
In some embodiments, the release mechanism is selectively reconfigureable to a releasable mode and a non-releasable mode.
In some embodiments, the release mechanism is selectively reconfigureable by selectively inserting a pin in different holes.
In some embodiments, the release mechanism includes a releasable pin that is U-shaped.
In some embodiments, the release mechanism is capable of being reset to its operative position without the use of tools.
In some embodiments, the first member and the guide member completely separate from each other upon moving from the operative position to the dislodged position.
In some embodiments, the guide member is pivotal about the retaining member.